2,3,5-substituted-6-trifluoromethyl-1,3-diazin-4-ones

ABSTRACT

Herbicidal compounds are disclosed having the general formula:   WHERE X is hydrogen or hydroxy, R1 is hydrogen or halo and R2 is alkyl, cycloalkyl, phenyl, alkenyl, and substituted derivatives of the above. Compounds for which herbicidal usage is claimed may include, in addition to the compounds of formula (I), formula (I) compounds in which R2 is hydrogen.

Unite States Patent 1 1 Lutz et al.

[45.] Mar. 4, 1975 I 2,3,5-SUBSTlTUTED-6-TRIFLUOROMETHYL-l,3-DIAZIN-4-ONES [75] Inventors: Albert William Lutz,Princeton;

Bryant Leonidas Walworth, Pennington, both of NJ.

[73] Assignee: American Cyanimid Company,

Stamford, Conn.

[22] Filed: Mar. 24, 1972 [2!] Appl. No.: 237,936

Related US. Application Data [63] Continuation-in-part of Ser. No.737,308, June 17,

1968. abandoned.

[52 US. Cl 260/260, 260/251 R, 71/92 [51] Int. Cl. C07d 51/30, C07d51/38 [58] Field of Search 260/251 R See particularly pp. 3280 and 3283.

J.A.C.S. 80, 5750(1958).

Primary E.\'mn inerD0naId G. D'aus Assistant E.\'aminerAnne Marie T.Tighe Attorney, Agent, or FirmH. G. Jackson [57] ABSTRACT Herbicidalcompounds are disclosed having the general formula:

where X is hydrogen or hydroxy, R is hydrogen or halo and R is alkyl,cycloalkyl, phenyl, alkenyl, and substituted derivatives of the above.Compounds for which herbicidal usage is claimed may include, in additionto the compounds of formula (I), formula (I) compounds in which R ishydrogen.

7 Claims, No Drawings This is a continuation-in-part of application Ser.No.

737,308, filed on June 17, 1968 now abandoned.

SUMMARY OF THE INVENTION This invention relates to novel2,3,5-substituted-6- trifluoromethyl-l,3-diazin-4-ones having theformula:

ifi;

wherein:

R is hydrogen or halo,

R is alkyl, cycloalkyl, phenyl, alkenyl and substituted derivatives ofthese radicals, and

X is hydrogen or hydroxy.

The various R groupings referred to hereinabove may be more particularlyidentified as follows.

The term alkyl means straight and branched chain alkyl radicalscontaining from 1 to 12 carbon atoms; illustrative members include loweralkyls" but also include other members such as pentyl, hexyl, heptyl,octyl, nonyl, decyl, undecyl, dodecyl, Z-methylhexyl, 3,3-dimethylpcntyl, triisopropylmethyl, and l-ethylpropyl.

The term cycloalkyl" means saturated cyclic structures containing from 3to 8 carbon atoms; illustrative members are cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.

The term alkenyl means unsaturated straight and branched hydrocarbonchains containing from 2 to 6 carbon atoms; illustrative members areallyl, 2-butenyl and Z-methylallyl.

The term halo means chlorine, bromine, iodine, and fluorine.

The terms substituted alkyl, substituted cycloalkyl, substitutedalkenyl, substituted phenyl,

The term carbalkoxy is limited to the lower alkoxys as defined above;illustrative members are carbomethoxy, carboethoxy, carbopropoxy, andcarbobutoxy.

Certain of the inventive compounds, i.e., those wherein X is hydroxyand/or when R is hydrogen may exhibit tautomeric forms such as thoseshown by way of example below:

\V F30 H F30 I t 1 /NH 6 R1 R.

Such tautomeric structures are included within the scope of theinvention as are the water soluble salts, particularly the sodium,potassium and ammonium salts, or the compounds and tautomers.

These salts are readily formed by a conventional acid-base reaction ofthe appropriate uracil with a base. Suitable bases include, for example,sodium or potassium hydroxide. The ammonium salts are prepared by usingammonium hydroxide or a C -C tertiary amine, such as trimethyl ortriethylamine as the base. The acid-base reactions are usually conductedin a solvent such as water.

Certain of the inventive compounds, i.e., those where X is oxygen, arecommonly denoted as uracils" while other inventive compounds, i.e.,those where X is hydrogen, are commonly denoted as 4(3H)- pyrimidinones.Although both types of compounds may be designated as substituted1,3-diazin-4-ones, the more common nomenclature of uracils and 4(3H)-pyrimidinones will be used in naming the compounds hereinafter.

The following are illustrative of the compounds of the invention:

3-methyl-5-bromo-6-(trifluoromethyl)uracil3-propyl-5-bromo-6-(trifluoromethyl)uracil3-nonyl-5-bromo-6-(trifluoromethyl)uracil3-dodecyl-5-bromo-6-(trifluoromethyl)uracil 3-cyclopropyl-5-chloro-6-(trifluoromethyl )uracil 3-cyclohexyl-5-chloro-6-(trifluoromethyl)uracil3-cyclobutyl-5-chloro-6-(trifluoromethyl)uracil3-phenyl-5-methoxy-6-(trit'luoromethyl)uracil3-(2-carbomethoxypropyl)-5-flu.oro-6- (trifluoromethyl)-uracil3-isopropyl-6-(trifluoromethy])uracil 3-decyl-6-(trifluoromethyl)uracil3-cyclopentyl6-(trifluoromethyl)uracil3-(2-butenyl)-6-(trifluoromethyl)uracil3-allyl-6-(trifluoromethyl)uracil 3-phenyl-6-(trifluoromethyl)uracil3-(4-chlorobutyl)-6-(trifluoromethyl)uracil3-(l-ethylpropyl)-6-(trif1uoromethyl)uracil3-(3-bromo-2-methoxypropyl)-6- (trifluoromethyl)uracil3-(m-trifluoromethylphenyl)-6- (trifluoromethyl)uracil 3-(2,4-dichlorophenyl )-6-(trifluoromethyl )uracil 3(2-carbomethoxypropyl)-6-( tr'ifluoromethyl )uracil3-methyl-5-chloro-6-trifluoromethyl-4( 3H pyrimidinone3-isopropyl-5-chloro-6-trifluoromethyl-4( 3 H pyrimidinone3-hexyl-5-chlor0-6-trifluoromethyl-4( 3H)- pyrimidinone 3-octyl5-bromo-6trifluoromethyl-4(3 H)- pyrimidinone l3-dodecyl-5-bromo-6-trifluoromethyl-4( 3H pyrimidinone3-cyclobutyl-5-bromo-6- trifluoromethyl-4( 3H )-pyrimidinone3-cyclohexyl-5-iodo-6-trifluoromethyl-4( 3H 3 pyrimidinone3-allyl-5-fluoro-6-trifluoromethyl-4( 3H pyrimidinone3-tolyl-5t-butoxy-6-trifluoromethyl-4( 3H pyrimidinone 3-(l-ethylpropyl)--bromo-6-trifluoromethyl-4( 3H pyrimidinone3-methyl-6-trifluoromethyl-4( 3H )-Pyrimidinone3-propyl-6-trifluoromethyl-4( 3H)-pyrimidinone3-isopropyl-6-trifluoromethyl-4( 3H )-pyrimidinone3-isobutyl-6-trifluoromethyl-4( 3H )-pyrimidinone3-hexyl-6-trifluoromethyl-4( 3H)-pyrimidinone3-octyl-6-trifluoromethyl-4( 3H )-pyrimidinone3-undecyl-6-trifluoromethyl-4( 3H )-pyrimidinone3-cyclohexyl-6-trifluromethyl-4( 3H )-pyrimidinone3-cyclopropyl-6-trifluoromethyl-4( 3H pyrimidinone3-allyl-6-trifluoromethyl-4( 3H )-pyrimidinone 3-( 2-butenyl)-6-trifluoromethyl-4( 3H )-pyrimidinone 3-phenyl-6trifluoromethyl-4( 3H)-pyrimidinone 3-benzyl-6-trifluoromethyl-4( 3H )-pyrimidinone 3-(2-methoxyethyl)-6-trifluoromethyl-4( 3H pyrimidinone 3-(l-ethoylpropyl)-6-trifluoromethyl-4(3H)- pyrimidinone -ethylpropyl)- 3-(2-bromopropyl)-6-trifluoromethyl-4(3H pyrimidinone 3-( 2,3-dibromopropyl)-6-trifluoromethyl-4( 3H)- pyrimidinone 3-( Z-carbomethoxypropyl)-6-trifluoromethyl4( 3H pyrimidinone 3-(3-bromo-2-methoxypropyl)-6-trifluoromethyl- 4(3H )-pyrimidinone3-tolyl-6-trifluoromethyl-4( 3H )-pyrimidinone 3-( 3.4-dichlorophenyl)-6-trifluoromcthyl-4( 3H pyrimidinone 3-( m-trifluoromethylphcnyl)-6-trifluoromethyl- 4( 3H )-pyrimidinone 3-( p-carboxyphenyl)-6-trifluoromethyl-4( 3 H pyrimidinonc 3-( 2-nitrophenyl)-6-trifluoromethyl-4( 3H pyrimidinone 3(p-aminophenyl)-6-trifluoromethyl-4( 3H pyrimidinone The compounds for which aherbicidal usage is claimed may be similarly represented by formula (1)hereinabve with the provision that R may be additionally hydrogen. Itshould be noted therefore that the herbicidal usage claims are ofbroader scope that the compound claims since certain compounds wherein Ris hydrogen are known, although the use of these compounds as herbicidesis not known. Additional details (1) cu s in this regard are provided inthe following portion of the specification.

THE PRIOR ART The compounds 6-(trifluoromethyl)uracil and 5-nitro-6-(trifluoromethyl)uracil are disclosed in J. Org. Chem. 24, 113(1959). 6-Trifluoromethyl-4(3H)- pyrimidinone is disclosed in J. AM.Chem. Soc. 80, 5750 (1958). In none of the above references is anyutility stated for the compounds. These reference compounds and readilyprepared derivatives thereof have therefore been specifically excludedfrom the compound claims appended hereto; however, the referencecompounds are embraced within the herebicidal usage claims.

It should be noted that none of the reference compounds containsubstitution in the number 3 ring position. It is known that direct andselective organic substitution of the number three nitrogen in al,3-diazine ring is usually unavailing since substitution will occur atother available ring positions to produce an undesirable productmixture. This route therefore could not be satisfactorily employed toproduce selective organic substitution on the number 3 nitrogen ascalled for in the novel compounds of this invention.

The preferred method of selectively substituting a diazine ring with anorganic substituent is to cyclize straight chain compounds which containthe desired organic substituent positioned on the proper atom prior tocyclization. The reference compound, 6- (trifluoromethyl)uracil wasprepared in this manner by condensing ethyl trifluoroacetoacetate withurea or thiourea respectively to produce the appropriate ringstructures. It might appear that if substituted ureas containing organicsubstituents were used in this reaction in place of unsubstituted ureas,uracils containing organic substitution on the number 3 nitrogen mightbe readily prepared. Surprisingly the reaction fails to proceed to anyappreciable extent with such substituted ureas. Since the5-nitro-6-(trifluoromethyl)uracil and the6-trifluoromethyl-4-(3H)-pyrimidinone were simply prepared by treating6-(trifluoromethyl)uracil by hitherto known techniques, it is thepreparation of the basic uracil ring structure which is the importantsynthesis step. Therefore the first problem encountered in producingformula (I) compounds in the synthesis of a uracil ring containing thedesired organic substituent in the number 3 nitrogen position.

U.S. Pat. No. 3,235,257 presents a process for preparing6-(alkyl)uracils containing organic substitution on the number 3nitrogen. The two step process is shown in the following equations:

CH3 0 C ll NCO-- Cll C=d 6001i rhi (i=0 riac 'a '(B) 3 0 I H H C (2) cne=c coca M NaOH 8 NH 3) HCl 1 H30 C=O- NEE-.23 5. Step l occurs in asolvent such as benzene or toluene,- 10

followed by filtration to remove solids, and evaporation. of the residuewhich removes the solvent from the fil-' trate to leave impure compound(B).

It might appear that this process would be readily adaptable topreparing similar 6- (tirfluoromethyl)uracils by merely replacing themethyl group on the amino carbon in compound (A) with a trifluoromethylgroup. However, when this was tried, reaction step (1) failed to proceedto any appreciable extent.

It becomes apparent that the simultaneous occurrence of organicsubstituents on the number 3 nitrogen and the presence of atrifluoromethyl grouping in the formula (I) compound is a barrier totheir preparation :by related prior art processes. These barriers areconveniently overcome by practicinga novel single step process describedhereinbelow.

US. Pat. No. 3,235,357 further discloses uracil structures which areuseful herbicides. For example, certain of these compounds replace thetrifluoromethyl group of Formula (I) compounds with chloro, bromo,chloroalkyl, and bromoalkyl. There are, however, several importantaspects of these reference compounds which .differ from the compounds ofthis invention. The reference compound does not refer to trifluoromethyluracil .since it is specifically limited to bromo and chloroderivatives. Furthermore, as the number 6 ring substituent is changedfrom monochloroalkyl to trichloroalkylsubstitution, herbicidal potencyof the reference compounds diminishes. Such results conflict with thehigh NH R t) I l CF 0 =C- C--OR herbicidal potency observed with the 6-trifluoromethyl-l,3-diazin-4-ones of this invention.

The reference compounds, while potent herbicides generally, do notexhibit a high degree of desirable selective herbicidal activity wherebyuseful vegetation such as farm crops is spared devastation whileundesir- .able plants growing among the crops are destroyed.

being the subject of a copending application of A. WI

Lutz, Ser. No. 737,288, filed concurrently herewith,

now US. Pat. No. 3,580,913 dated May 25, 1971 and assigned to thepresent assignee.

In accordance with this process, 6-(trifluoromethyl)- uracils of theformula:

H F g N O wherein R is as previously defined, and R is limited tohydrogen and water soluble salts of said compounds and tautomersthereof, are conveniently prepared by reacting an ester of aB-amino-Ctfi-Uflsatuffltttd acid of the formula:

NH; R 0

I i n 3 CF C C-COR or tautomers thereof, with an isocyanate of theformula:

R NCO wherein R is lower alkyl and R, R are as defined immediatelyhereinabove, in the presence of a solvent and an alkali metal hydride oralkali metal lower alkoxide. The reaction proceeds in accordance withthe following equation:

H F N O R NCO R N-R +R OH (III) Reactant isocyanate (III) is readilyprepared by a variety of hitherto known methods. The reactant acid ester(II) is likewise conveniently prepared by known techniques such as thatof Jouille, in J. Org. Chem. 21, 1358 (1956).

It is an important aspect of this process that it be performed in thepresence of an inert solvent and a solvent-soluble highly alkaline baseto insure the satisfactory progression of the reaction.

Among the solvents which are suitable are aromatic solvents containingfrom 6 to 8 carbon atoms such as toluene, benzene, xylene; loweralkanols containing from I to 8 carbon atoms such as methanol, ethanol,isopropanol, butanol, pentanol, octanol, t-butanol; low molecular weight(i.e., a molecular weight not exceeding about 200) glycol ethers such asdiethylene glycol dimethyl ether (diglyme), ethylene glycol dimethylether (glyme), diethylene glycol diethyl ether, and ethylene glycoldiethyl ether; and dipolar aprotic solvents, i.e., solvents which aresubstantially chemically inert toward reactants (11) and (111) as wellas product (1), which have a coordinated valence link between twooriginally neutral atoms whereby one loses and the.

other gains a share of two electrons, and which neither yields a protonto the solute, nor gains one from it. lllustrative dipolar aproticsolvents are dimethylsulfoxide (a highly preferred solvent),dimethylformamide, acetone, methyl isobutyl ketone, acetonitrile,nitrobenzene, N,N-dimethylacetamide, and the tetrahydrosulfolanes suchas tetrahydrothiophene dioxide.

Suitable bases are potassiumtertiary butoxide (the preferred base),sodium methoxide, sodium propoxide, sodium hydride, potassium hydride,and lithium hydride. A preferred amount of base is about 0.9 to about1.1 moles per mole of reactant.

A highly preferred solvent-base system is that of dimethylsulfoxide andpotassium tertiary butoxide because of the increased product yieldsobserved therewith. The solvent-base system, however, is not limited toa single solvent and base and may include combinations such as a singlebase with more than one solvent, a single solvent with more than onebase, or simultaneously more than one solvent and more than one base.

The process appears insensitive to pressure and may be carried out atatmospheric, sub-atmospheric or superatmospheric pressures. Temperaturesbetween about 15C. and about 100C. are suitable. Preferred;

conditions are atmospheric pressure and a temperature range of about25C. to about 50C.

The products (I) prepared by this process may be readily converted intotheir corresponding acid or base such as shown by way of illustration inExamples 19-31,

hereinbelow.

When it is desired to prepare 4(3H)-pyrimidinones Example No. ReaetantIsocvanate l 2 methyl OH ethyl 0H embraced within formula (1), thecorresponding uracil may be prepared as described above. Then using wellknown methods, the oxygen on the number 2 ring position can be removedto leave the desired 4(3H)- pyrimidinone.

The following examples are provided to further illustrate the invention.

EXAMPLE 1 Preparation of 3-isopropyl-6-(tirfluoromethyl)uracils Asolution of ethyl 3-arnino-4,4,4-trifluorocrontonate (10.7 g., 0.058mole) in 20 ml. of anhydrous dimethyl sulfoxide was added in portionswith stirring to a solution of potassium tert-butoxide (8.55 g., 0.058mole) in 50 ml. dimethyl sulfoxide. Cooling was required to maintain thetemperature at 25C.

lsopropylisocyanate (5.48 g., 0.64 mole) was added all at once withvigorous stirring to the above solution. After one hour the yellowsolution was poured into a large volume of water and this solutionextracted three times with ether. The ether layers were discharded. Theaqueous phase was acidified to pH 1 with hydrochloric acid and thenextracted three times with ether. After washing the ether extract withwater, drying and stripping in vacuo, a pale yellow solid residue of11.3 g. (87.0%) remained. The product was recrystallized from water togive the analytical sample which had a melting point of l39-142C.

CnHgF1|N202 requires: C, 43.

found- 3 EXAMPLES 2 15 Following substantially the same procedure asthat of Example 1, except for variations in reactant isocyanate used,the compounds presented in Table l were prepared.

TABLE I Example No.

Reactant Isocyanate 4 n-propyl 5 n-butyl 6 sec-butyl 7 't-butyl 8n-octyl 9 n-dodecyl l cyclohexyl 11 phenyl l2 5,4-dichlorophenyl lcarbethoxymethylene A allyl l5 l-fluorophenyl l6 E-fluorophenyl l7B-fluorophenyl l8 B-trifluoromethylphenyl EXAMPLE 19 Preparation of3-isopropyl-5-bromo-6- H F C N 3-isopropyl-6-(trifluoromethyl)uracil asprepared in Example 1 (7.4 g., 0.033 mole) was dissolved in a mixture of0.5N NaOl-l (0.04 mole) and chloroform m1.). A solution of bromine (5.89g., .036 mole) in ml. chloroform was added in portions with stirring.After the addition was complete, the reaction mixture was stirred forone-half hour before discharging the bromine color with sodiumbisulflte. The layers were separated, and the aqueous layer extractedwith fresh chloroform. The combined chloroform extracts were washed withwater and then evaporated to dryness leaving 10.1 g. (100%) of whitesolid residue. One recrystallization from benzene gave a product with amelting point of l46l50C. The analytical sample melted at 149-150C.

C,,H,.BrE-,N O requires: C, 31 92; H, 2.67; Br, 26.54;

F. 18.93; N, 9.30 found: C, 31.94; H, 2.68; Br 26.56;

31 R2 Melting Point. (*c.)

H n-e, H7 -174 H sec-C1, H9 106. 5-108 H -ct 165-167 H n-C1 2 H 5121-125 H 0 -197 H Cl 255-256.5 H G 258-259 H CH2 500 H5 149-1505 H caCH=CH2 5158-160 H @F 188-189 -Continued EXAMPLES 20-31 Followingsubstantially the same procedure as that of Example 19, 5-bromoderivatives of the compounds prepared in Examples 2 to 13 were prepared.Melting points are presented in Table 11.

1 l 12 dibromopropyl)-6-(trifluoromethyl)uracil was simi- EXAMPLES 34 To35 larly prepared, melting point: l54155.5C.

EXAMPLE 32 Preparation of 5brm'6'(trifluoromethynuracil Followingsubstantially the same procedure as that of met y raci 2-, 91 was Eample 3 3, the following compounds were prepared:

Example No. Compound Melting Point Q C. 2

H F 0 N 0 I T 158-141 Q, N-cHwH, Cl

no H o H F C N OH F, c .N 0 5 I l Br NH Br N H W fl ...WM... Q

dissolved in 75 ml. water at 70C. Bromine (3.55 g., UTILITY 0.022 mole)was added in portions with vigorous stirring. A white precipitate formedalmost immediately. The suspension was allowed to cool to roomtemperapounds whgrem R2 may be addltlonauy hydr0ge.n.are ture and thenchilled before being filtered. The product effecnve preemergence andpostemergence herblcldes after air drying weighed 475 g. (825 70) andhad a useful for the control of monocotyledonous and dicotymelting pointof 23143400 The analytical Sampleledonous plants as amply shown by thedate of Examt t .ples 36 and 37 hereinbelow. gg lf gr was A er recrys ama Ion Application of the compounds of the invention for purposes ofherbicidal control can be accomplished employing both conventional typeformulations and C ',H2Br2F..N20 requires: C, 23.19; H, 0.78; N. 10.82;40 equipment. The compounds may, for instance, be formulated as wettablepowders, dusts, dust concentrates, emulsifiable concentrates and thelike which are amenable to application with conventional spraying ordusting apparatus.

Wettable powder formulations are generally pre- The inventive compoundsas well as formula (1) com- Br, 30.86 found: C, 23.04: H. 0.89; N, lL05;

EXAMPLE 33 pared by admixing from about 25% to about by Preparation of5-chloro-3-n-butyl-6- weight, of active ingredient with finely groundclay, (trifluoromethyl)uracil such as kaolin or attapulgite, eitherwithor without a F} E o F, c N on A I 01 N411. -a *v- 01 N H9 23-n-butyl-6-(trifluoromethyl)uracil (1.0 g.) was dissurface activeagent, emulsifier or spreader-sticker. solved in 15 ml. of 5.25% sodiumhypochlorite solution The latter is then dispersed in water for sprayapplicaand allowed to stand at room temperature for one hour. tion. Thesuspension which was present was acidified to pH Dusts and dustconcentrates are similarly prepared 1 with hydrochloric acid and thesolid removed by fil- 0 using from about 5% to about 95% of activeingredient tration. After purification by chromatography and reand fromabout 95% to about 5% of finely divided inert crystallization fromcyclohexane, the product had a ingredients. These dusts are generallyapplied as such, melting point of l38C.-l39C. or they may be furtherdiluted with finely ground inert solids and then applied withconventional dusting appa- Q IUCIFQMO, requires: c, 39.94; 1-1. 3,72;Cl, 13.10; 65 ratus.

found i523 3 5 I299. Emulsifiable concentrates may be prepared bydissolving or dispersing the active ingredient in organic solvent, withor without emulsifying agents, surfactants or the like. Suchformulations are then diluted with eil 10 20% reduction in stand therwater or an appropriate organic diluent prior to O no apparent effectapplication. g V 7 a abnormal, malformed, twisted The followingadditional examples are provided to. c chlorotic illustrate theherbicidal activity of the compounds. g usual Physiological effect mmoderate injury EXAMPLE 36 r regrowth PRE-EMERGENCE HERBICIDAL ACTIVITYOF s severe j y SUBSTlTUTED-6-TRIFLUOROMETHYL1,3- I trace to slightinjury DlAZIN-4-ONES no test The preemergent herbicidal activity of theCom; Abbreviations for the plant species employed in the pounds isexemplified by the following tests in which i j 'f activity tests ofExamples 36 and 37 are the seeds of a variety of monocotyledonous anddicoty- O ledonous plants are separately mixed with potting soil and themixture placed on top of several inches of pot- Rag Ragweed Cor =Cornting 5011 in separate pint cups. After planting, the cups K0 Kochia g fgg are sprayed with the selected aqueous-acetone solution hij fgig sfig rig ets containing the test compound in sufficient quantity to Pi PigweedAW =Alligator Weed provide the desired equivalent of four poinds peracre 2? :gfgggi :ggggfi of test compound per cup. The treated cups arethen GF =Green Foxtail JG =Joh Grass placed on greenhouse benches andcared for in the W0 =w'ld Oats g3 usual manner, in accordance withgreenhouse proceg dures' Three Weeks 9 tratmcm the tests are icrmkCompounds identified by l| were rated according to nated and each cup 18examined and rated according to the followin ting System the definedl-lcrbitoxicity lndex given in the table beg I low. The tabulatedresults of these tests presented in Table III establish the herbicidalproficiency of the test "/1 Difference in Growth compounds. RatingSystem from the Check 0 ff or 0 Herbitoxicity Index 1 Saga; effect 2slight effect 1 1-25 9 l00% reduction in stand I 3 moderate ff 2640 9- lor 2 stunted plants remaining 5 definite injury 41-60 109mmvigifiilfifliiifiim as 7 70" 85% reduction in stand 8 approachingcomplete kill 91-99 6 reduction in stand 9 complete 4 abnormal growth,l.e.. a definite physiological mal- 5 60% reducnon m Stand formation butwith an over-all effect less than a 5 4 40 50% reduction in stand on theWing Scale- 3 30- 40% reduction in stand '-B"d -ld -r f't'd,. .m th 2 2030% reduct on In stand 40 mul bririi ios i nii sjcr-uii gifii ig mznclWe 6 0mm grow TABLE IIl. PRE-EMERGENCE HERBICIDAL DATA AT A DOSAGE OF 4LB./ACRE X R1 R2 E5 352 E 2 El 29. l HQ Q2 Q3. A!

on H CH3 3 9 9' 9 9- 9 mg 9 mg 0 m 0 OH H a s 9 9 9 9 9' 9" 9 9 0 9 8 9OH H a 9 9 9 9 9' 9 a 9 m 9 0a a i-CaH 9 9 9 9 9 9 mg 9 8 9 0a a 11-0 119 9- 9 8 8 8g 8g t o m o 9 OH H 4 9 9 9 9 9' 9 9 9 g 9 9 9 OH H r1C H 05g 96 3g mg mg 3g 8 O O to O OH H n-C H 0 9 9 0 5g mg 9 s tg r O 1'. 1:50a a 3 9 9' 9 7g 7s a s 0 0 9 m9 8 0a a Q 9 9 9 9 3g 83 mg 9 mg 9 9 9 :1on it c1 9 9 9 9 3s 9 e 0 s 9 7 9 OH H cu coc n tg 5 9- o 5 9 9 0 0 o 09 TABLE III. CONT'D Cor Cot S02 n-CgH Cl o n CHZCOCZHS duce the desiredconcentrations of about four pounds per acre of active compound whenapplied to the plants through a spray nozzle operating at psi for apredetermined time. After spraying. the plants are placed on Thepostemergence herbicidal activity of the compounds is demonstrated bytreating a variety of monogreenhouse benches and are cared for in theusual mancotyledonous and dicotyledonous plants with the comner,commensurate with conventional greenhouse pounds dispersed inaqueous-acetone mixtures. In the practices. Two weeks after treatment,the seedling test seedling plants are grown in jiffy flats for about twoplants are examined and rated in Table IV below acweeks. The testcompounds are dispersed in 50/50 cording to the Herbitoxicity Indexprovided in Example acetone/water mixtures in sufficient quantity topro- $6.

sec-C 3 the tautomers and water soluble sodium, potassium, ammonium andtri(C -C alkyl) ammonium salts.

2. The compound according to claim 1 wherein X is .hydroxy, R ishydrogen and R is alkyl having from I to l2 carbon atoms.

3. The compound according to claim 1 wherein X is hydroxy, R is chloroor bromo and R is alkyl having from 1 to 12 carbon atoms.

1. A COMPOUND OF THE FORMULA
 2. The compound according to claim 1wherein X is hydroxy, R1 is hydrogen and R2 is alkyl having from 1 to 12carbon atoms.
 3. The compound according to claim 1 wherein X is hydroxy,R1 is chloro or bromo and R2 is alkyl having from 1 to 12 carbon atoms.4. The compound according to claim 1:3-isopropyl-6-(trifluoromethyl)uracil.
 5. The compound according toclaim 1: 3-isopropyl-5-bromo-6-(trifluoromethyl)uracil.
 6. A compoundaccording to claim 1: 3-isopropyl-5-chloro-6-(trifluoromethyl)uracil. 7.A compound according to claim 1 wherein X is hydroxy, R1 is hydrogen andR2 is p-fluorophenyl of m-trifluoromethylphenyl.